Dear Miss Joy:

An "Apostolic Bull" is a solemn apostolic letter that begins with the name of the Pope and deals with important subjects such as conferring the titles of bishops and cardinals, to promulgate canonizations, to proclaim Holy Years, and for other purposes.

The "bull" comes from the Latin bulla (seal), since a lead or waxen seal is affixed to the decree.

An "Apostolic Brief" (Breve) is a papal letter of less formality than a bull, and is given a stamped representation of the Seal of the Fisherman, and signed by a Curial Secretary. Breves are usually issued for beatifications and other matters.

An "Apostolic Constitution" is the highest and most authoritative form of papal legislative pronouncement (or conciliar pronouncement). A Constitution promulgates law with binding force.

Constitutions issued by ecumenical councils may on doctrinal or pastoral issues, but either way are binding upon the whole church. The four Constitutions of Vatican II are: Church, Liturgy, Revelation, and Church in the Modern World.

A "Decree" is an edict or ordinance

1. issued by a pope or ecumenical council with binding force on the whole church, or
2. issued by a Curial Department with binding force for the concerned parties, or
3. issued by a territorial body of bishops with binding force for the people in that area, or
4. issed by an individual bishop with binding force for concerned parties until revocation or death of the bishop.

There were nine Decrees issued by Vatican II.

A "Declaration" is an ecclesiastical document that makes interpretation of current existing law; or can be a position paper on a specific topic. The three Declarations of Vatican II are: Religious Freedom, Non-Christian Religions, and Christian Education.

An "Encyclical" is a letter usually addressed to the Bishops of the world, but sometimes addressed to the all the faithful. Encyclicals express the mind of the Holy See on matters of greater importance. There are two type of encyclicals -- "letters" and "epistles". The "Letters" are the most often given and are the more formal of the two. "Letters" are to the whole church; "epistles" are addressed to only part of the Church.

Encyclicals generally concern matters of doctrine, morals, or discipline, or significant commemorations.

Encyclicals are letters of authority. Pope Pius XII in the encyclical Humani generis August 12, 1950 stated:

Nor must it be thought that what is contained in encyclical letters does not of itself demand assent, on the pretext that the popes do not exercise in them the supreme power of their teaching authority. Rather, such teachings belong to the ordinary magisterium, of which it is true to say: 'He who hears you, hears me' (Lk 10:16); for the most part, too, what is expounded and inculcated in encyclical letters already appertains to Catholic doctrine for other reasons."

While it is possible a Pope may speak ex cathedra though an encyclical, we must keep in mind that the teachings of the Pope must be submitted to, even if not ex cathedra.

Vatican II declared:

"Religious submission of will and of mind must be shown in a special way to the authentic teaching authority of the Roman Pontiff, even when he is not speaking ex cathedra. That is, it must be shown in such a way that his supreme magisterium is acknowledged with reverence, the judgements made by him are sincerely adhered to, according to his manifest mind and will. His mind and will in the matter may be known chiefly either from the character of the documents (one of which may be an encyclical), from his frequent repetition of the same doctrine, or from his manner of speaking" -- Dogmatic Constitution on the Church, no. 25).

An "Instruction" is a document containing doctrinal explanations, directive norms, rules, recommendations, admonitions. Instructions can be issued by the Pope, a Curial Department, or other competent authorities in the Church. To the extent that they so prescribe, Instructions have the force of law.

A "Motu Proprio" is a document issued by a pope on his own initiative. These usually deal with administrative matters.

There are other documents known by various names that are issued to clarify or interpret laws, to explain papal declarations and letters, and the like.

I hope this helps.

God Bless,
Bro. Ignatius Mary